Singleton in Swift example

ItemStore.swift

// More info: http://code.martinrue.com/posts/the-singleton-pattern-in-swift

import UIKit

class ItemStore {
    
    class var sharedInstance: ItemStore {
        
        struct Static {
            static var instance: ItemStore?
            static var token: dispatch_once_t = 0
        }
        
        dispatch_once(&Static.token) {
            Static.instance = ItemStore()
        }
        
        return Static.instance!
    }
    
    private var items = [Item]()
    
    func createItem() -> Item {
        var newItem = Item.randomItem()
        
        items.append(newItem)
        
        return newItem
    }
    
    func allItems() -> [Item] {
        return [Item](items)
    }
}